Levaquin is already among the stockpile of antibiotics, but federal health authorities are aiming for an expanded approval of Levaquin, to provide faster treatment in plague scenarios of bioterrorism or natural occurring outbreaks. To accomplish expanded approval, the “Animal Rule” (Code of Federal Regulations 314.610) has been recommended by an advisory panel reviewing the matter this week. The rule allows the FDA to rely on the evidence from studies in animals to provide substantial evidence of effectiveness, where human evaluations are not appropriate for approval.
The panel overwhelmingly agreed that studies performed on monkeys provided substantial evidence of Levaquin’s effectiveness in treating pneumonic plague. While this recommendation does not mean final acceptance by the FDA, the recommendations are typically followed. A final decision by the agency is expected later this month.
Yersinia pestis (Y. pestis), the causative agent of plague, has several characteristics that make it a significant concern for use as a biological weapon: it can be found in many regions of the world, can be mass-produced, and can be disseminated through direct aerosolization. The pathogen can be spread through person-to-person contact and therefore has high potential for secondary spreading during an epidemic. Additionally, the pneumonic form of the disease has rapid onset of signs and symptoms and has a very high fatality rate. All of these characteristics are key factors underlying its classification as a Category A Bioterrorism Agent in the U.S.
Currently, there are no FDA-approved antibacterials specifically indicated for the treatment of pneumonic plague (resulting from the direct inhalation of Y. pestis) for adult or pediatric use. Neither are there any approved vaccines for plague caused by Y. pestis. The FDA granted priority review status of the Supplemental New Drug Applications for the pneumonic plague indication to Janssen Research & Development, LLC (a Johnson & Johnson subsidiary) in December 2011.